He began his rugby union career in 2001, playing for Orrell, before moving to Harlequins three years later. He began playing for the England national team in 2007, playing in the 2007, 2011 and 2015 Rugby World Cup, as well as the annual Six Nations Championships. Aged 38, he confirmed his retirement in 2016.
Easter is the brother of Sale Sharks player Mark Easter and the nephew of author Anne Easter Smith. His father, John, played squash professionally and reached No. 1 in Britain and No. 9 in the world. His great grandfather, Pieter Le Roux, played for the Springboks. He attended the South London public school Dulwich College and Nottingham Trent University.
After a period working in London, Easter moved to Rosslyn Park F.C. before moving onto Orrell. In 2004, Easter signed for Harlequins.
Easter has won the Harlequins Player of the year award four times in 2004–05, 2005–06, 2012–13 and 2014–15 season at the age of 36.
In the penultimate game of the 2013–14 season, against Bath, Nick became the most capped Harlequin in the professional era with 233 appearances.
After 15 seasons, 54 international appearances and a record 281 appearances for Harlequins, Easter announced his retirement on 29 July 2016.
Easter made his England debut in the 2007 Six Nations win against Italy.
On 4 August 2007, Easter scored four tries as England beat Wales by a record 62–5 at Twickenham in a World Cup warm-up game. Easter was the first No.8 to score four tries in one match for England.
He started 6 matches of the 2007 Rugby World Cup where he was a key influence in helping make the final.
During the 2008 Six Nations he was named man of match against France away in Englands 24–13 win. He also started all 5 matches of the 2009 Six Nations.
On the 2010 England tour to Australia he was named man of the match in the second test victory 21–20, helping secure England's first win down under for seven years. Later that year he captained his country during the autumn internationals against Samoa which England won 26–13.
He won the 2011 Six Nations, despite England losing 24-8 to Ireland which meant they missed out on the grand slam. In spite of the defeat however, he lifted the Six Nations trophy as England ended their 8-year wait for a title.
He was involved in the 2011 Rugby Union World Cup and was reported to be the player to have reacted to England's quarter-final defeat by France in Auckland by joking: "There's £35k just gone down the toilet."
Between 2012-2014, despite being regarded as the 'best No. 8 in England', he found his road into the England squad blocked, but during that time enjoyed success with Harlequins helping them to win the Amlin Cup in 2011 and the club's first-ever English Premiership title in 2012 and LV Cup the following year.
After being in the international wilderness for just over three-years Nick was recalled to the England squad for the 2015 Six Nations. In the opening game he came on as a substitute for England in their 21–16 win over Wales at the Millennium Stadium in Cardiff. In the second game, he scored a try against Italy and thus became the oldest player ever to score for England. He won his 50th cap away to Ireland.
After being overlooked for the initial 31-man England squad for the 2015 Rugby World Cup, Easter was called up as an injury replacement for Billy Vunipola. He put in a Man of the Match performance in England's final World cup game against Uruguay, scoring 3 tries.
Following his retirement from professional rugby, in July 2016, it was confirmed that Easter had been appointed as the new defence coach at Harlequins.
Easter has appeared in three separate episodes of BBC One sport quiz programme A Question of Sport.